The present invention is drawn to an improved gas injection nozzle design for use in a swirling tank reactor used in the degassing of molten metal with a fluxing gas.
An improved method and apparatus for degassing molten metal is disclosed in U.S. Pat. No. 4,177,066 to Joseph A. Clumpner and assigned to the assignee of the instant invention. The disclosure in the aforenoted patent teaches degassing molten metal using an apparatus comprising a swirling tank reactor wherein molten metal is tangentially introduced into the reactor so that the molten metal flows in a swirling rotating fashion as the metal passes from the inlet of the reactor to the outlet thereof. In order to achieve the desired swirling flow of molten metal from the metal inlet to the metal outlet of the reactor, it is required that the metal inlet be positioned with respect to the chamber wall of the reactor in such a manner as to tangentially introduce the liquid into the reactor. In a preferred embodiment, the swirling tank reactor comprises a first elongated substantially cylindrical sidewall portion and a second downwardly converging sidewall portion beneath the first substantially cylindrical wall portion. Fluxing gas inlet nozzles penetrate the converging wall portion at different heights thereof so as to optimize fluxing gas bubble dispersion through the entire melt as it passes from the inlet of the reactor to the outlet thereof. By positioning the nozzles at different heights in the converging wall portion, the fluxing gas nozzles are in turn located at various distances from the center axis of the swirling tank reactor thereby maximizing fluxing gas bubble dispersion. The specific details of the various embodiments of swirling tank reactors and nozzle locations disclosed in U.S. Pat. No. 4,177,066 may readily employ the improved gas injection nozzle design of the present invention and the disclosure of U.S. Pat. No. 4,177,066 is incorporated hereby by reference.
While the above-noted swirling tank reactors disclosed in U.S. Pat. No. 4,177,066 are superior to other known prior art inline degassing apparatuses, a number of problems have been encountered with fluxing gas nozzle designs. In particular, metal leakage from the reactor around the nozzle tip has been experienced. In addition, a problem has been encountered with leakage in the fluxing gas delivery line itself. Finally, it has been found that the nozzles tend to break off when they project through the chamber wall and into the tank proper.
U.S. Pat. No. 4,392,636 to Joseph A. Clumpner, assigned to the assignee of the instant invention, discloses a gas injection nozzle for use in the swirling tank reactor disclosed in U.S. Pat. No. 4,177,066. The gas nozzle design comprises a nozzle insert secured in the wall of the swirling tank reactor and flush with the inner circumference of said wall. The nozzle insert is provided with a seating surface adapted to receive a nozzle tip cone made of a ceramic material or the like. The fluxing gas nozzle is spring biased against the nozzle tip cone with adequate force to seal the nozzle against the tip cone and the tip cone against the nozzle insert so as to prevent metal leakage from the reactor around the fluxing gas nozzle. The fluxing gas nozzle is secured to the fluxing gas supply line by means of a nozzle screw assembly employing a seal between the nozzle screw assembly and the fluxing gas nozzle. It has been found that the rotational movement of the nozzle screw assembly on the seal between the nozzle screw assembly and the fluxing gas nozzle is detrimental to effective sealing. As the swirling tank reactor is designed for the removal of hydrogen and alkaline earth metals from molten aluminum and employs active gases such as chlorine and the like it is imperative that a leak-proof design for delivering the fluxing gas be developed.
U.S. Pat. No. 4,494,735 to Robert E. Hershey, assigned to the assignee of the instant invention, discloses a gas injection nozzle for use in a swirling tank reactor of the type described above. The gas nozzle design comprises a nozzle insert secured in the wall of the swirling tank reactor and flush with the inner circumference of the wall. The nozzle insert is provided with a seating surface adapted to receive a nozzle tip cone made of a ceramic material or the like. The fluxing gas nozzle is biased against the nozzle tip cone with adequate force to seal the nozzle against the tip cone so as to prevent metal leakage from the reactor around the fluxing gas nozzle. The fluxing gas nozzle is secured to the fluxing gas supply line by means of a nozzle screw assembly which comprises a nozzle nut which receives the nozzle blank. The nozzle nut receives in a non-rotational manner a clamp plate which presses against a seal provided between the clamp plate and the rear of the nozzle blank. A male screw member is threadably received in the nozzle nut and biases the clamp plate against the seal and correspondingly the nozzle blank to effect a leak-free seal. A spring washer may be provided between the clamp plate and the male screw to aid in biasing the clamp plate. While the nozzle assembly of the '735 patent initially operated without any leakage problem, over time leakage has occurred due to destruction of tip cone gasket materials.
Accordingly, it is a primary object of the present invention to provide an improved gas injection nozzle design for delivering a gaseous material which is free of leakage in the gas delivery line.
It is the principal object of the present invention to provide an improved gas injection nozzle design for use in a swirling tank reactor used in the degassing of molten metal with a fluxing gas.
It is a particular object of the present invention to provide an improved gas injection nozzle design for use in a swirling tank reactor used in the degassing of molten metal wherein gas leakage around the nozzle tip is eliminated.
It is a still a further object of the present invention to provide an improved gas injection nozzle design provided with the improvements as aforesaid which is convenient and inexpensive to utilize.
Further objects and advantages of the present invention will appear hereinbelow.